1. Field of the Invention
The field of art to which this invention pertains is radiation curable compositions. In particular, this invention relates to radiation curable solventless ink compositions.
2. Description of the Prior Art
Typical of this prior art is U.S. Pat. No. 3,551,311 issued Dec. 29, 1970, having Nass, Bassemir and Carlick as co-inventors. That patent relates to a radiation curable solvent-free composition which consists essentially of an ester produced from the reaction of an ethylenically unsaturated acid and a polyhydric alcohol, and a photoinitiator comprising a halogenated aromatic alicyclic or aliphatic hydrocarbon initiator. These two components when combined in weight ratios taught by the patent produce a radiation curable composition possessing particular useful characteristics. Such materials may be incorporated into coatings used on metals, plastics, textiles, paper, cardboard, or as a marking composition for roads, airfields or similar surfaces.
However, the rather simple two-component system described above does have certain limitations. The primary difficulty with such a photoreactive system has been rather poor gloss and wet rub resistance of the cured composition. Additionally, the toughness of such systems after curing has been found to be poor in many instances.
The present novel improvement eliminates such deficiencies by the addition to such prior art systems of a vinyl and hydroxyl containing polymer and in particular a polymer of a vinyl aromatic and an unsaturated alcohol. Such polymer improves the wet rub resistance, gloss and toughness of the cured system making such systems a practical coating which can be used in the printing industry.